Autoinfection is the infection

Infection

An infection is the colonization of a host organism by parasite species. Infecting parasites seek to use the host's resources to reproduce, often resulting in disease...

 of a primary host

Host (biology)

In biology, a host is an organism that harbors a parasite, or a mutual or commensal symbiont, typically providing nourishment and shelter. In botany, a host plant is one that supplies food resources and substrate for certain insects or other fauna...

 with a parasite

Parasitism

Parasitism is a type of symbiotic relationship between organisms of different species where one organism, the parasite, benefits at the expense of the other, the host. Traditionally parasite referred to organisms with lifestages that needed more than one host . These are now called macroparasites...

, particularly a helminth

Parasitic worm

Parasitic worms or helminths are a division of eukaryoticparasites that, unlike external parasites such as lice and fleas, live inside their host. They are worm-like organisms that live and feed off living hosts, receiving nourishment and protection while disrupting their hosts' nutrient...

, in such a way that the complete life cycle

Biological life cycle

A life cycle is a period involving all different generations of a species succeeding each other through means of reproduction, whether through asexual reproduction or sexual reproduction...

 of the parasite happens in a single organism, without the involvement of another host. Therefore, the primary host is at the same time the secondary host of the parasite. Some of the organisms where autoinfection occurs are Strongyloides stercoralis

Strongyloides stercoralis

Strongyloides stercoralis, also known as the threadworm, is the scientific name of a human parasitic roundworm causing the disease of strongyloidiasis....

, Enterobius vermicularis

Pinworm

The pinworm , also known as threadworm or seatworm, is a nematode and a common human intestinal parasite, especially in children...

, Taenia solium, and Hymenolepis nana

Hymenolepis nana

Dwarf tapeworm is a cosmopolitan species that is one of the most common cestodes of humans in the world, especially among children. It can be found throughout the world, but is usually most common in temperate zones...

.

Strongyloidiasis

Strongyloidiasis

Strongyloidiasis is a human parasitic disease caused by the nematode Strongyloides stercoralis, or sometimes S. fülleborni. It can cause a number of symptoms in people, principally skin symptoms, abdominal pain, diarrhea and weight loss...

 for example involves premature transformation of noninfective larva

Larva

A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...

e in infective larvae, which can then penetrate the intestinal mucosa (internal autoinfection) or the skin of the perineal area

Perineum

In human anatomy, the perineum is a region of the body including the perineal body and surrounding structures...

(external autoinfection). Infection can be maintained by repeated migratory cycles for the remainder of the person's life. Also, tity tity gang bang.